Heterogeneous communication system and method for circuit switched handover

Abstract

A heterogeneous communication system of performing a handover from a WiMAX communication system to a LTE communication system includes a UE adapted to request a handover connection establishment to the LTE communication system while receiving a CS service from the WiMAX communication system, request an authentication to the first WiMAX system, preferentially perform the handover to the LTE communication system, and switch to the LTE communication system in response to a handover message; and a GANC adapted to deliver the request of the handover connection establishment to the LTE communication system, notify the procedure of the authentication to the LTE communication system and provide the handover command message to the UE to switch to the LTE communication system, thereby providing the CS service to the UE through the LTE communication system. A handover from an LTE communication system to a WiMAX communication system is also disclosed.

1 . A heterogeneous communication system of performing a handover from a first communication system to a second communication system integrated therein, the heterogeneous communication system comprising:
 a user equipment (UE) adapted to request a handover connection establishment to the second communication system while receiving a CS (Circuit Switched) service from the first communication system, request an authentication to the first communication system, preferentially perform the handover to the second communication system after the authentication, and disconnect a connection with the first communication system and switch to the second communication system in response to a handover message; and   a generic access network controller (GANC) adapted to deliver the request of the handover connection establishment to the second communication system, notify the procedure of the authentication to the second communication system, and provide the handover command message to the UE to switch to the second communication system, thereby providing the CS service to the UE through the second communication system.   
     
     
         2 . The heterogeneous communication system of  claim 1 , wherein the UE is further adapted to perform a registration update and subscriber data retrieval on the first communication system via GANC, transmit a handover complete notification message to the second communication system to notify a completion of the handover and establish a RTP path with the GANC after the completion of the authentication. 
     
     
         3 . The heterogeneous communication system of  claim 2 , wherein the GANC is further adapted generates a relocation request message based on the handover request received from the UE to provide the relocation request message to the second communication system, and generate the handover command message based on a relocation command message provided from the second communication system in response to the relocation request message. 
     
     
         4 . The heterogeneous communication system of  claim 2 , wherein the second communication system is adapted to provide an authentication request message to the GANC; perform a location update and subscriber information retrieval on the first communication through the GANC; sets up a default bearer; establishes an RRC connection between the UE and the second communication system through the GANC; establish an evolved packet system (EPS) bearer in response to the relocation request message from the GANC; and provide the relocation command message to the GANC. 
     
     
         5 . The heterogeneous communication system of  claim 1 , wherein when the UE cannot perform the handover from the second communication network to the first communication network, the GANC is adapted to request the second communication system to release resources previously reserved for the handover and delete relevant UE location information. 
     
     
         6 . The heterogeneous communication system of  claim 1 , wherein the first communication system is a worldwide interoperability for microwave access (WiMAX) communication system and the second communication system is a long term evolution (LTE) communication system. 
     
     
         7 . A heterogeneous communication system of performing a handover from a first communication system to a second communication system integrated therein, the heterogeneous communications system comprising:
 a user equipment (UE) adapted to form an authentication with the second communication system, perform a handover preparation to the second communication system to establish a traffic connection for a CS (Circuit Switched) service, disconnect a connection with the first communication system and switch to the second communication system, and perform a radio link initial access and basic capability negotiation with the second communication system; and   a generic access network controller (GANC) adapted to deliver a message related to the authentication to the second communication system, after the authentication is performed, transmit a context information for the UE to the second communication system to establish the traffic connection, perform a registration update and establish the RTP path with the UE to provide the CS service, thereby providing the CS service to the UE through the second communication system.   
     
     
         8 . The heterogeneous communication system of  claim 7 , wherein the GANC is further adapted to transfer context information for the UE to the second communication system after the completion of the authentication. 
     
     
         9 . The heterogeneous communication system of  claim 7 , wherein when the UE cannot perform handover from the second communication system to the first communication system, the GANC is adapted to request the second communication system to release resources previously reserved for the handover and delete relevant UE location information. 
     
     
         10 . The heterogeneous communication system of  claim 7 , wherein the first communication system is a long term evolution (LTE) communication system and the second communication system is a worldwide interoperability for microwave access (WiMAX) communication system. 
     
     
         11 . A method for performing a handover from a first communication system to a second communication system in a heterogeneous communication system having a generic access network controller (GANC), the method comprising:
 in the GANC, delivering a request of a handover connection establishment from a user equipment (UE), which receives a CS (Circuit Switched) service from the first communication system, to the second communication system;   in the GANC, notifying an authentication between the UE and the first communication system to the second communication via the GANC;   in the UE, preferentially performing the handover of the UE to the second communication system through the first communication system after a connection to the second communication system is completed;   in the UE, in response to a handover command message, disconnecting a connection to the first communication system and switching to the second communication system; and   in the UE, performing a resource reservation to the second communication system to receive the CS service from the first communication system through the second communication system via the GANC.   
     
     
         12 . The method of  claim 11 , further comprising:
 in the second communication system, performing location update and subscriber data retrieval on the first communication system via the GANC;   in the UE, performing a default bearer setup on the second communication system via the GANC; and   in the UE, establishing an radio resource control (RRC) connection with the second communication system via the GANC.   
     
     
         13 . The method of  claim 11 , wherein the first communication system is a worldwide interoperability for microwave access (WiMAX) communication system and the second communication system is a long term evolution (LTE) communication system. 
     
     
         14 . A method for performing a handover from a first communication system to a second communication system in a heterogeneous communication system having a generic access network controller (GANC), the method comprising:
 in the GANC, delivering an authentication-related message between the second communication system and a user equipment (UE), which receives a CS (Circuit Switched) service from the first communication system;   in the UE, delivering a handover preparation message to the second communication system via the GANC to establish a traffic connection for the CS service after the authentication;   in the UE, switching to the second communication system,   in the UE, performing a radio link initial access and basic capability negotiation with the second communication system;   in the second communication system, providing an unsolicited registration response message to the UE via the GANC in response to the radio link initial access and basic capability negotiation; and   in the UE, in response to the unsolicited registration response message, performing a registration update to the GANC and establishing the RTP path to receive the CS service from the GANC.   
     
     
         15 . The method of  claim 14 , wherein the first communication system is a long term evolution (LTE) communication system and the second communication system is a worldwide interoperability for microwave access (WiMAX) communication system.